1. Field
The present invention relates generally to a high-efficiency digital transmitter. More particularly, the present invention relates to a digital radio-frequency (RF) transmitter that is optimized for linear quantized in phase and quadrature (IQ) up conversion.
2. Description of the Related Art
Digital power amplifiers can be designed for various quantization schemes. The preferred digital quantization scheme for digital power amplifiers is to quantize the power. In addition, the angle of the digital power amplifiers can be adjusted by controlling the phase angle of a radio frequency (RF) drive circuit to each digital power amplifier. The combination of the quantized power and the varied angle to each digital power amplifier maps nonlinearly to the linearly quantized in phase (I) and quadrature (Q) components of baseband signals. Increasing the quantization levels can achieve a reasonable approximation; however, the process is complicated and does not yield accurate results. Thus, it is difficult to implement a digital RF transmitter that is optimized for linear quantized IQ up conversion.
Thus, there is a need for a low cost high-efficiency digital RF transmitter that is optimized for linear quantized IQ up conversion.